There are numerous risks to women’s fertility to conceive, as well as, increased risks during pregnancy from obesity, and these risks increase with the degree of obesity. Obesity is defined as a pre-pregnancy BMI > 30 Kg/m^2. While diabetes mellitus (DM) increases with obesity, there is still an increase in complications and adverse pregnancy outcomes in obese women who do not have diabetes.
The prevalence of obesity in reproductive age women has increased similar to the general population. The 2011-2012 National Health and Nutrition Examination Survey (NHANES) found the incidence of obesity to be 31 % in adults age 20 to 39. This was increased to 56.6 % in non-Hispanic black people. In contrast (before BMI was routinely used), in 1980 only 7% of women weighed over 200 pounds at their first pre-natal visit.
There are several effects of obesity on fertility. A common cause of infertility is anovulation secondary to PCOS (polycystic ovarian syndrome), which can be treated with weight loss, and Metformin to reduce insulin resistance. However, even regularly ovulating obese women have lower spontaneous pregnancy rates and a longer time to pregnancy. During treatment for infertility, obese women require higher doses of medications for ovulation induction. They have lower pregnancy rates with IVF, possibly due to effects on oocyte quality, ovarian function and endometrial receptivity. Obese women using an egg donor have similar pregnancy rates as non-obese women using an egg donor, suggesting that obesity may have effects on egg quality. There are also confounding factors such as male partner obesity, smoking, fat distribution and other associated pathologies.
Perinatal issues with obesity include an increase in miscarriage independent of fetal aneuploidy (abnormal chromosomes) and may be related to PCOS and insulin resistance. There is an increase in both Gestational Diabetes (GD) as well as type 2 diabetes mellitus (DM). Pregnancy Associated hypertension and pre-eclampsia also intensify with increasing maternal weight and BMI. Pre-pregnancy bariatric surgery has been shown to decrease diabetes and pre-eclampsia in obese pregnant women. There is also an increase in miscarriages as well as indicated pre-term birth secondary to hypertension, pre-eclampsia and diabetes. Obesity also carries a heightened risk of extreme pre-term birth and delivery (22-27 weeks gestation), along with an increase in post-term pregnancy, twins, urinary tract infections and obstructive sleep apnea (OSA).
During labor and delivery, obese women have an increase in dysfunctional labor, induction of labor and less successful VBACs (vaginal birth after C-section). They have a greater chance of Caesarian delivery (both elective and emergency) with subsequent increase in post-partum hemorrhage, wound infection, venous thromboembolism, DVT (deep vein thrombosis) and PE (pulmonary embolism). Complications of anesthesia as well shoulder dystocia from a very large fetus (macrosomia) are also intensified with obesity.
Perinatal outcomes are suboptimal with an upturn in congenital anomalies in babies such as NTDs (neural tube defects such as spina bifida) even with folic acid supplementation. In addition, there are increased defects such as cardiovascular anomalies, cleft lip and palate, anorectal atresia, hydrocephalus and limb reduction anomalies. A fetus is also at risk for prematurity, death, asthma and autism spectrum disorders.
Pre-pregnancy recommendations for the obese woman include weight loss prior to conception through diet, exercise, behavior modification and bariatric surgery as well as the limitation of weight gain during pregnancy. Bariatric surgery is best for women less than 35 years old; it has very good results, but pregnancy must be delayed for at least 2 years until nutritional issues have stabilized. Women over age 35 have “biologic clock” issues and may not want to wait 2 years to conceive.
Sometimes egg freezing is a viable option to do prior to bariatric surgery to not push off that biological clock further.
Also, we have nutritional people we work with to help patients be successful in their weight loss, so they can proceed with treatment. Sometimes a relatively small amount of weight loss can be sufficient. For further information on how nutrition affects your fertility, please contact us to book an appointment at (973) 322–8286 or fill out our contact form and we will contact you shortly.